Lesson 11: Chi-Square Tests

Objectives

Upon successful completion of this lesson, you should be able to:

  • Construct a chi-square probability distribution plot in StatKey or Minitab Express
  • Determine when a chi-square goodness-of-fit test and chi-square test of independence should be conducted
  • Compute and interpret expected counts
  • Conduct chi-square tests by hand and using Minitab Express
  • Calculate and interpret relative risk

In this lesson we will learn how to compare the proportions of more than two independent groups and how to test for a relationship between two categorical variables. In this lesson you will also review risk and odds and learn about relative risk.

Before we begin, let's review the various classifications of variables from Lesson 1:

Categorical
Names or labels (i.e., categories) with no logical order or with a logical order but inconsistent differences between groups, also known as qualitative.
Quantitative
Numerical values with magnitudes that can be placed in a meaningful order with consistent intervals, also known as numerical.

In this lesson we will be examining methods for analyzing categorical variables.